1. Field of the Invention
The present invention relates to a printing apparatus in which an ink ribbon cartridge is detachably mounted, and more specifically to a device for identifying the ink ribbon cartridge used in the printing apparatus.
2. Description of the Prior Art
An ink ribbon cartridge for use in a thermal printer is well known in the art. The ink ribbon cartridge includes a casing and at least one spool having an ink ribbon thereon. There are provided various kinds or ink ribbons with different characteristics, which are selectively used depending upon a printing operation mode such as multicolor or monochrome printing, the type of a recording medium, etc. Therefore, the ink ribbon cartridge now mounted may be replaced with another one having a desired ink ribbon, if necessary. An information mark indicating the characteristic of the ink ribbon mounted is detected by a sensor disposed within the printer so that the printing operation is controllably performed on the basis of the detected information mark. Conventionally, the information mark is recorded on the casing of the ink ribbon cartridge in a manner such as embossing or optical marking. One of example of an ink ribbon cartridge with such an information mark is disclosed in Japanese Patent Application First Publication No. 63-254085.
However, many sensors must be provided for detecting many information marks and thereby the printer necessitates a relatively large space in which the sensors are accommodated. Japanese Patent Application First Publication No. 2-20368 discloses an ink ribbon cartridge including a spool with an information mark which indicates specific characteristics of the ink ribbon. The information mark is provided on a peripheral surface of the spool. The spool rotates to feed the ink ribbon wound thereon so that the information mark on the spool is detected by the sensors fixedly mounted in the printer. A printing operation starts subsequent to the detection of the information mark. In addition, Japanese Patent Application First Publication No. 1-85787 discloses an ink ribbon cartridge including a spool with a timing mark which serves for detecting the number of rotations of the spool. A remaining amount of the ink ribbon unused is ascertained on the basis of the detected number of rotations of the spool.
However, since a portion of the ink ribbon must be unwound from the spool to allow detection of the information mark prior to the start of the printing operation, a portion of the ink ribbon is made unavailable for the printing operation and thereby causes an undesirably amount of wasted ink ribbon unless the ink ribbon is wound back on the spool. If many information marks on the spool must be detected, the amount of required rotation of the spool increases so that an amount of the wasted ink ribbon increases. In a case where a device for reversing the spool is provided for preventing the waste of the ink ribbon, the printer is complicated in the structure. Further, in such a case, the rewound ink ribbon in unused state tends to be damaged during reversing operation.
An object of the present invention is to provide a device for identifying an ink ribbon cartridge without rotating a spool.
Another object of the present invention is to provide a printing apparatus capable of detecting information marks recorded on an ink ribbon cartridge without complicating its structure.